As TTDegs suggests, your warranty still covers for issues on parts untouched.If you were to buy sideskirts for example, have them bonded to the existing bodywork and have them sprayed while on the vehicle, you may have problems claiming for a later paint issue on the doors for example, as they may have been oversprayed by yourself or the fitters of the skirts.Most companies including Nissan will uphold warranty only items fitted inhouse.For example, if lowereing springs, front lip, skirts, diffuser, spoiler, wheels etc are in an accessories catalogue by Nissan and you have them all fitted by a Nissan Dealership, then any issues are resolved under warranty.On the other hand...If you blow the turbo because you ar running a piggyback ecu and have too much boost then thats down to you!Be aware that the more tuning/styling you decide to do, the less dealerships will want to take responsibility for.I altered my Swift Sport so far from standard form that the local dealer wouldn't even service it because they didn't recognise a majority of items in the engine bay!